China was worried that "Petronas has carried out a major activity at an area that is also claimed by China," Anwar said in response to a parliamentary question about his discussions on the South China Sea during his visit to China last week.

"I stressed... that Malaysia sees the area as Malaysian territory therefore Petronas will continue its exploration activities there," Anwar said, without specifying an offshore project or a location.

But if China feels this is their right, Malaysia is open for negotiations, Anwar said, reiterating comments made earlier this week.

China claims almost the entire South China Sea as its territory via a "nine-dash line" on its maps, which cuts into the exclusive economic zones of Vietnam, the Philippines, Malaysia, Brunei and Indonesia.

Malaysia's foreign ministry will issue a protest note if there were "collisions" between Malaysian and Chinese vessels in the area, Anwar said.

The Chinese embassy in Kuala Lumpur was not immediately available for comment.

(Reporting by Rozanna Latiff; Editing by Martin Petty)